Question

an elements X who atomic number is 20 mass number is equal to 40 find me and valency metal or nonmetal​

Answer 1

Answer:

• Valency of element X is 2
• Element X is "Metal"

Explanation:

$According \: \: \: to \: \: \: the \: Question$

It is given that ,

• Element X whose atomic number = 20
• Mass number = 40

we have to calculate the valency and decide whether it is metal or non metal.

Firstly we find the name of element X

As per given condition the mass of element X is 20 and its mass is 40

So, the elements will be Calcium .

Electronic Configuration of Calcium

Ca = 2,8,8,2

Now, we know that valency of an element is calculated " The number of electrons present in last orbit of an element "

Here, in last orbit of calcium 2 electrons are present .

• So, valency of element X is 2

Since ,2 electrons present in its last orbit so it like to loose 2 electrons from its orbit to gain it stability/noble gas configuration .

And , the elements which loose electrons to gain stability are generally Metal .

• Hence, the element X is a "Metal" .

Answer 2

To find :

If element X is a metal or non metal . and, what is its valency.

Given :

• Atomic mass = 40
• Atomic number = 20

Solution :

Given, Atomic number = 20

Atomic mass = 40 .

The element at 20th position in a periodic table is Calcium (Ca).

it is a Metal (Alkaline earth )

It have 20 proton

Hence, X is a metal (calcium) .

Electrons per shell in Ca :

2,8,8,2

The metal Ca needs to remove 2 electrons from it to be stable or gain a octate like noble gases.

hence, Valency = 2

Hence, your Answer :

• The element is Calcium (Ca)
• It is a Metal
• valency = 2